Haemolysis Flashcards
What are causes of immune haemolytic anaemia? Describe haemolytic disease of the newborn
Autoimmune Transfusion reaction Haemolytic disease of the newborn: Mother is RhD- and baby is RhD+ - mother is exposed to RhD+ blood which results in IgM production - this can't cross the placenta. On second exposure IgG is produced which can cross placenta so following fetus gets erythrocytes destroyed. Ante-natal anti-D prophylaxis given Bone marrow transplant
What are causes of mechanical haemolytic disease?
Heart valves - shearing
Thrombotic thrombocytopenia purpura
DIC
What are hereditary haemolytic diseases
Red cell membrane defects:
Spherocytosis
Eliptocytosis
G6PD deficiency - cross linking - disulphide bridge Hb aggregates, heinz bodies form, haemolysis
Sickle cell anaemia
Thalassaemia
what are acquired haemolytic diseases?
Haemolytic disease of newborn
Incompatible transfusion
Autoimmune:
Warm: IgG binding cells at 37 degrees
Drugs, leukaemia, SLE,
Cold: IgM bidding celsla t less than 37c
Non immune
Hypersplenism
Sepsis
Prosthetic heart valves
What tests for haemolysis?
Blood film - spherocytes, schistocytes, Direct coombs' test Bilirubin - raised Lactate dehydrogenase - raised Raised reticulocytes Urinary haemosiderin in haemolytic anaemia
What is direct Coombs’ test?
TEst for autoimmune haemolytic anaemia - wash red blood cells, add anti-human globulin which binds RBCs if they are bound by hosts IgG - positive if cells then agglutinate which means they have autoimmune haemolytic anaemia
What are causes of microcytic anaemia?
THALIS Thalassaemia Anaemia of chronic disease Lead Iron deficiency Sideroblastic anaemia - rare congenital does not respond to iron
What should you do if you suspect iron deficiency? What are the causes? How do you treat?
- Measure ferritin (contains iron, therefore low in iron-deficiency anaemia, but an acute phase protein so may be high in inflammation anyway – false negative)
- Serum iron and transferrin saturation
• Think about the cause
o Inadequate intake – vegetarianism or veganism
o Increased loss – GI bleeding or menorrhagia
o Excessive use – pregnancy
• Treat o Dietary advice o Oral supplements o Intramuscular iron injections o Intravenous iron o Transfusion (if severe with imminent cardiac compromise)
When should you take iron supplements?
Iron supplements are absorbed in the duodenum and jejunum. Maximal absorption is in the first few weeks of treatment – it is enhanced by ascorbic acid, and inhibited by antacids, H2 blockers, PPIs, tetracyclines, calcium and phytates. You should take it between meals.
You should anticipate a rise in Hb by 2g/dl in three weeks, a clinical improvement in symptoms, changes in the reticulocyte count, increase in mean cell volume and increase in serum ferritin.
What are causes of macrocytic anaemia?
• B12 deficiency – it takes many years to become deficient.
o Vegetarians & vegans
o Gastric causes (pernicious anaemia – autoantibody against intrinsic factor) and intestinal causes
o Give oral or IM hydroxycobalamine
• Folate deficiency – takes months to become deficient
o Diet
o Malabsorption
o Excessive use (sickle cell anaemia, hereditary spherocytosis)
o Drugs – anticonvulsants, co-trimoxazole, methotrexate, sulfasalazine, alcohol
• Myelodysplasia (but youd expect other dysplastic features on the film)
• Hypothyroidism
• Pregnancy
• Liver disease - alcohol excess
What are causes of B12 and folate deficiency?
B12 deficiency – it takes many years to become deficient.
o Vegetarians & vegans
o Gastric causes (pernicious anaemia – autoantibody against intrinsic factor which is required to absorb B12 from the terminal ileum - this is secreted from stomach parietal cells so gastrectomy can cause B12 deficiency) and intestinal causes
o Give oral or IM hydroxycobalamine B12
• Folate deficiency – takes months to become deficient
o Diet
o Malabsorption
o Excessive use (sickle cell anaemia, hereditary spherocytosis)
o Drugs – anticonvulsants, co-trimoxazole, methotrexate, sulfasalazine, alcohol
What should you check in a macrocytic anaemia?
- Check B12 and folate
- Check TFT and LFTs
- Check immunoglobulin levels (myeloma, monoclonal gammopathy of undetermined significance (MGUS))
- May consider bone marrow biopsy for myelodysplasia
Where are iron, folate and B12 absorbed?
Due Is Just Feeling Ill Bro
Duodenum - iron
Jejunum - folate
Ileum - B12 - with intrinsic factor from the stomach
What are causes of normocytic normochromic anaemia?
Acute blood loss
• Anaemia of chronic disease – associated with chronic inflammation or infection, which results in cytokines reducing serum iron by increasing hepcidin levels – this reduces gut iron absorption and increases the amount of iron moved into stores. You also get reduced erythropoietin production and a reduced lifespan of red blood cells. You would get
o Normocytic or microcytic anaemia
o Normal or raised ferritin
o Reduced serum iron
o Normal transferrin saturation (if reduced suggests concomitant iron deficiency)
• Mixed deficiency of iron and B12/folate
• Bone marrow failure (although usually macrocytic)
Pregnancy
How do you investigate normocytic anaemia?
If you get normocytic anaemia you would first rule out treatable causes:
• Nutritional – B12, folate, Iron (measure ferritin too)
• Haemolysis – bilirubin, lactate dehydrogenase, haptoglobin, reticulocytes, blood film
• Renal disease (urea and electrolytes)
• Bleeding
And then based on whether or not you suspect haemolysis:
• If you suspect haemolysis you should refer to a specialist
• If you don’t:
o Anaemia of chronic disease?
o Primary bone marrow disorder?
o You can distinguish by the history, CRP and abnormalities in FBC.
